Can someone explain please???

[Innulja]

Which substance can act only as a reducing agent?
a) I2
b) BrCl
c) NaBr
d) HIO4

Thanks to everyone who will make an effort!

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[WOAHHI]

wow where is this question from? I didn't even know BrCl exists -_-... I know the answer can't be HIO4 tho xD

 

[Philippines03j]

First there is a trend that says that the better oxidizing agents are To the right and up(like ionization energy) which would leave C as being the correct answer. Is that right?

 

[Innulja]

The answer is C.
Yea I didn't know the BrCl exists either lol. Is the periodic trend the only way to answer this question?
Please explain I really want to learn this!!!

 

[WOAHHI]

i never heard of this trend before... should i be worried -_-..? so the trend for reducing agents is to the bottom and left?

 

[Philippines03j]

Ok, let me re-explain this trend correctly. I had it only partially correct.

1. Strongest oxidizing agent is left to right and bottom to top(like ionization). In other words going toward F.

2. Strongest Reducing agent is from right to left and bottom to top. In other words going towards Li.

I am not sure if I could fully explain it anyother way but maybe someone else can.

 

[sixkiller]

Which substance can act only as a reducing agent?
a) I2
b) BrCl
c) NaBr
d) HIO4

Thanks to everyone who will make an effort!

A REDUCING agent is oxidized. The answer is C because Na+ is in its highest possible oxidation state therefore it can't be oxidized. Bromide however is in the -1 oxidation state, thus it can be oxidized and therefore, NaBr can ONLY act as reducing agent.

Choice A) iodine is 0 oxidation state. Therefore, it can be either oxidized or reduced.

Choice B) Br-Cl bromine has a +1 oxidation state and chlorine has a -1 oxidation state; thus either oxidation or reduction is possible for bromine and only oxidation is possible for chlorine. Therefore, the compound itself can act as either a reducing agent or oxidizing agent.

Choice D) iodine is in the highest possible oxidation state +7 thus iodine can only be reduced. H has a +1 oxidation state and can only be reduced and oxygen has a -2 oxidation state and can only be oxidized. The compound can therefore act as either oxidizing or reducing agent.

 

[Innulja]

Thanks everyone for their input.
Sixkiller and Philippines03j thanks for the explnations, all of it now comes together🙄

 

[Meas]

How can you conclude that oxidation or reduction is possible for bromine & oxidation is only possible for chlorine? When I think of oxidation states, I always thought column starting with Li has +1 & Be has +2, whereas column starting with F has -1, O has -2, N has -3, C has -4. Am I correct here?

Thanks!

A REDUCING agent is oxidized. The answer is C because Na+ is in its highest possible oxidation state therefore it can't be oxidized. Bromide however is in the -1 oxidation state, thus it can be oxidized and therefore, NaBr can ONLY act as reducing agent.

Choice A) iodine is 0 oxidation state. Therefore, it can be either oxidized or reduced.

Choice B) Br-Cl bromine has a +1 oxidation state and chlorine has a -1 oxidation state; thus either oxidation or reduction is possible for bromine and only oxidation is possible for chlorine. Therefore, the compound itself can act as either a reducing agent or oxidizing agent.

Choice D) iodine is in the highest possible oxidation state +7 thus iodine can only be reduced. H has a +1 oxidation state and can only be reduced and oxygen has a -2 oxidation state and can only be oxidized. The compound can therefore act as either oxidizing or reducing agent.

 

[Pat Kelly]

Nevermind, my understanding is not deep enough.

Bromine can go to +7, but chlorine is already at -1, so it can only oxidize, whereas bromine can oxidize to +7 or reduce to -1

where is this question from btw?

 

[sixkiller]

How can you conclude that oxidation or reduction is possible for bromine & oxidation is only possible for chlorine? When I think of oxidation states, I always thought column starting with Li has +1 & Be has +2, whereas column starting with F has -1, O has -2, N has -3, C has -4. Am I correct here?

Thanks!

There are two ways in which to calculate oxidation states....

One of the methods is to examine the Lewis Structure (most people either forget this method or were not taught this method for whatever reason).

Br-Cl is the lewis structure for the compound (both bromine and chlorine have 3 lone pairs).

Calculating the oxidation state for Br is 7 - 6 = +1

7 is the number of valence electrons for Br and 6 is the number of electrons surrounding the bromine with respect to the lone pairs (non-bonding electrons). The two bonding electrons are NOT included in this calculation because chlorine is MORE electronegative than bromine.

The oxidation state for chlorine is 7 - 6 -2 = -1

In the calculation, the bonding electrons essentially "belong" to the more electronegative atom.

Keep in mind that we are calculating oxidation states...not formal charges. The only similarity is that both the sum of oxidation states and the sum of formal charges is either equal to zero or the net charge of the molecule.

Practice this method with other molecules to get a feel for it.

*The oxidation states that you have listed are either maximum or minimum values....see the above post for the rules regarding oxidation states for various groups*

 

[MCATQUESTIONS]

A REDUCING agent is oxidized. The answer is C because Na+ is in its highest possible oxidation state therefore it can't be oxidized. Bromide however is in the -1 oxidation state, thus it can be oxidized and therefore, NaBr can ONLY act as reducing agent.

Choice A) iodine is 0 oxidation state. Therefore, it can be either oxidized or reduced.

Choice B) Br-Cl bromine has a +1 oxidation state and chlorine has a -1 oxidation state; thus either oxidation or reduction is possible for bromine and only oxidation is possible for chlorine. Therefore, the compound itself can act as either a reducing agent or oxidizing agent.

Choice D) iodine is in the highest possible oxidation state +7 thus iodine can only be reduced. H has a +1 oxidation state and can only be reduced and oxygen has a -2 oxidation state and can only be oxidized. The compound can therefore act as either oxidizing or reducing agent.

Why can't Na+ be reduced? Making it like Choice D?